There is widely known a load-gripping device mostly for sacked loads comprising a frame suspendable on the hook of a crane and an insertable rod member having a counterweight at one end, the suspension point of the frame being offset relative to its center of gravity (cf., e.g., USSR Inventor's Certificate No. 931,654, Int. Cl. B 66 C 1/58, 1982). The frame of the load gripping device is suspended on the hook of the hoisting mechanism so that this frame assumes an inclined position, and the device is brought closer to the neckof a packed sack. After this the sack neck is passed through the frame around the insertable rod, and then the free end of the sack neck under the rod is fed to the frame of the loading gripping device in the reverse direction. The operator holds by one hand the rod with the counterweight, and by the other hand manipulates with the sack neck. At the point of raising the packed sack the operator continues to hold the inseertable rod with the counterweight and the end of the sack neck until the sack is lifted from the ground.
After conveying the packed sack and lowerin it onto an even surface the insertable rod of the device slips out of a sling formed by the neck of the sack under the action of the counterweight, and the sack is disengaged from the load gripping device.
However, this device is inconvenient and complicated in operation due to that prior to clamping the sack nect is successively passed through the frame and around the insertable rod, and the free end of the packed sack is passed again under the rod in the reverse direction. As the sack is lifted, the operator has to stay too close to the packed sack, which is dangerous. Another disadvantage resides in that guaranteed slipping of the rod is not ensured as the sack is disengaged from the device, since displacement of the center of gravity of the insertable rod causes twisting of the neck sling, and the rod tends to be jammed in the sling. This results in less efficient operation of the device and poses danger to the attending operator.
Also, this load gripping device cannot be attached directly to the ends of the carrying elements of loaders having a limited hoisting height.
There is further known a device for gripping necks of packed sacks (cf., e.g., USSR Inventor's Certificate No. 1,009,970, Int. Cl. B 66 C 1/58, 1983) comprising a housing with a horizontal support, and a frame one side of which is pivotably connected to the housing. The pivot connecting one side of the frame to the housing is arranged above the horizontal support. The other side of the frame has a horizontal rod member. The frame is arranged inside the housing so that the axis of the frame is capable of vertical displacement. The housing has curvilinear guidess for the horizontal rod of the frame. The device is suspended on the hook of a hoisting mechanism, brought to the packed sack, and passed around the horizontal rod. The neck of the packed sack is fed to a clearance between the horizontal rod and horizontal suport of the device so as to grip the neck. Ends of the horizontal rod of the frame are placed under the curvilinear guides of the housing. The neck of the packed sack is therefore clamped and the sack is ready for hoisting. As the housing of the device is raised, the neck of the sack is pulled to force the horizontal rod of the frame to the horizontal support of the housing, and is clamped between these elements by a clamping force proportional to the weight of the sack. The weight of the sack causes the horizontal rod of the frame to rest under the curvilinear guides of the housing during transportation. The frame is locked in the low position.
After carrying the sack and placing it onto the surface the operator turns the frame, brings the horizontal rod of the frame from under the curvilinear guides of the housing, lifts the frame, and disengages the neck of the packed sack.
This device is inconvenient and inefficient in operation due to difficulties associated with holding the frame aside and fitting the neck of a packed sack in the gap between the horizontal rod of the frame and horizontal support of the housing.
Another disadvantage of this prior art device resides in excessive amount of labour required for its servicing, and lack of a unified arrangement for attaching the device to carrying elements of hoisting mechanisms of various constructions.